Trolley for third rails



No. 607,065 Patented luly l2, I898. r L. M. MAXHAM.

TRULLEY FOR THIRD RAILS.

(Application filed Sept. 1, 1897.)

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LOWELL MASON MAXHAM, OF BOSTON, MASSACHUSETTS.

TROLLEY FOR THIRD RAILS.

SPECIFICATION forming part of Letters Patent No. 607,065, dated July 12, 1898.

Application filed September 1, 1897- Serial No. 650,276. (No model.)

To ctZZ whom, it may concern:

Be it known that I, LOWELL MASON MAX- HAM, a citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented a new and useful Trolley for Third Rails, of which the following is a full,clear,and exact description.

The object of this invention is the construction of improved means for transmitting to the motor of an electric car the current flowing through the electroconductor contained in an elasticallyshielded third rail.

This device, which I will term a trolley, is specially designed for the form of third rail shown and described in my application for patent, Serial No. 639,636, allowed June 7, 1897 5 and it consists, essentially, of a resiliently-supported wheel adapted to traverse the center line of the third rail and provided with means whereby the motorman of the car can in an instant increase or diminish the pressure of said wheel, causing it to vary through all degrees from zero to the maximum pressure which may ever be required. Auxiliary to this I have designed such a form of trolley as will retain its position upon the center line of the third rail even when the car is passing about a curve independently of any groove or similar confining means.

Referring to the drawings forming part of.

this specification, Figure 1 is a sectional elevation of my trolley viewed upon the line X X in Fig. 2. Fig. 2 is a View thereof looking from beneath. Fig. 3 is a detail view of the trolley-bearings; Fig. 4, a part of the pivoted shank; Fig. 5, a cross-section of my third rail; and Fig. 6, a diagram showing relative positions of track, wheels, and trolley.

In the drawings, IV W represent two of the wheels of a four-wheel car-truck.

S T is a portion of the truck-frame.

R is the car-floor. It is one of the crossbeams thereof, and ris the swivel-post, whereby the truck is enabled to support its end of the car-body with the required degree of swiveling play.

In the form of electric tram-car to which mytrolley is shown as connected the motor is supposed to be carried by the truck at the other end of the car, leaving one truck free for the reception of the various parts of the trolley.

In my approved form of trolley I employ two trolley-wheels A A, revoluble in boxes B, carried at the extremities of the springarms 0, there being two of said arms for each trolley-wheel. These arms are rigidly held by the castings D D, which are both mounted upon the pivot-pin f, secured within the lugs F,depending from the plate F,the latter being bolted to the under side of the truck crossbar T. Said castings or pivoted shanks D D are provided at vertically-alined points thereof with the nuts e e, loosely held therein by means of the trunnions e, and turning in these nuts is the vertically-prolonged rod E, the part entering one of said nuts being threaded with a right-hand screw and the other with a left-hand screw, the nuts being internally threaded to correspond. Of course the terminal screw section must be made sufficiently smaller in diameter to pass freely through the upper and oppositely-threaded nut.

The upper extremity of the rod E being passed through a suitable aperture in the carfioor into the cab devoted to the motorman and being further provided with an actuating wheel or crank E the motorman can by a quick turn or two of the said wheel instantly force the two nuts 6 c toward or away from each other and correspondingly affect the pressure of the trolley-wheels A A upon the third rail, upon which they are traveling. This will be more apparent when we note that the separation of said nuts and the attached pivoted shanks DD tends to bring the centers of the trolley-wheels and the pivot-pin f more nearly into line, while their approach carries the said centers farther below said pivot-pin. This pivot-pin being held at a fixed height, the result of such angular variation of said shanks and the spring-arms carried thereby can only be to increase 'or diminish the pressure of the trolley-wheels upon the rail below.

The arms 0 are made resilient in order toallow for the variations in height of the third rail and the track-rails, although I have reduced the cause of variation between the trolley-support and the third rail as much as possible by attaching said support to the truck instead of to the car-body itself.

As shown in Fig. 1, the trolley-wheels A A are placed as near as is practicable beneath the axles V of the car-wheels W. The object of this is to retain the trolley-wheels as near as possible upon the center line of the track when the car is passing about a curve. At such times the center of the truck, and much more so of the car-body, is far to one side of the center line of the track; but since the Wheels are under the control of the trackrails the mid-points of their axles are at the nearest possible approximation to the desired median line, as indicated in Fig. 6. As is well known, the car-wheels are not in exact parallel with thetrack-rails at the points of contact when thus passing about a curve and are only held thereon by the wheel-flanges. The trolley-wheels being parallel with said car-wheels will have asimilar tendency to ride to one side of the third rail, and the springarms 0 being resilient vertically, thereby permitting one arm to rise slightly and the other to similarly be depressed, a trolley-wheel will tend to cant slightly and run toward the outer edge of the third rail, if it is the forward trolley-wheel we are considering. come this tendency, the trolley-wheel is made peripherallycrowning, as shown in Fig. 2, and is thereby caused to guide itself back toward the center of the rail in the same way that a frustum of a cone rolls toward its side of smallest diameter. To further overcome this tendency, I give a slight spiral twist to each spring-arm C, the arm at one side of a trolleywheel being twisted in one direction and the arm at the other side in the opposite direction. As is well known, a fiat spring when untwisting lengthens, and when twisting tighter is shortened. Hence any canting of a trolleywheel will, to a certain extent, untwist one spring-arm and twist up the other, thereby shortening the latter and lengthening the other. By thus moving one bearing-box forward and the other backward the trolleywheel will be turned to one side and thereby guided back toward the center line of the third rail. This twist is shown in Fig. 3 and the ball-bearings by which the trolley-wheel is allowed this angular play.

The object in having two trolley-wheels is mainly to insure continuous electrical contact with the conductor. Since in the form of third rail shown in my said application for patent the resilient plate is nondepressible at the terminal juncture between two sections thereof, a trolley-wheel at said point is out of circuit, and in thus making and breaking the circuit, as would be the case were but a single wheel employed, there would occur an objectionable sparking. Furthermore, in case the car stopped with its single trolley standing thus over a rail-joint and out of circuit no current could be obtained for the further propulsion of the car.

I usually insulate the boxes 13 from the spring-arms O and take the current directly from the boxes, as indicated in Fig. 1, and to further insure against any possible danger to To overthe motorman I also insulate the spring-arms 0 from the shanks D D, by which they are held. The said insulation is indicated by the letter of reference d in Figs. 1 and 4:, which latter figure shows more clearly how the spring-arm C is secured to the pivoted shank D.

My objectin putting the trolleys in and out of circuit by varying their pressure upon the third rail, as previously described, is to prevent there being any live rail beneath the car when it is at rest and there is no occasion for using the current. Were the current still flowing from the electroconductor to the car through the trolleys, a rail-section might be projecting beyond the end of the car which would be charged with the current and liable to cause injury to any one who might be crossing the track too near the car; but by thus removing the pressure of the trolleys from the third rail the latter is made absolutely dead and incapable of harming any one, whether passing close by the car end or even working beneath it.

Although I have described this trolley as applicable to a form of third rail in which a resilient plate guards the electroconductor from undesired contact, it is equally applicable to any other kind of third rail, and wherever I speak of varying the pressure of the trolley upon the third rail it will of course be understood as a variation extending from zero to the maximum pressure required-in other words, varying from a condition of noncontact to a definite pressure.

In Fig. 5 I have shown the form of third rail for which "my trolley is especially designed and which differs from that illustrated in my said application, Serial No. 639,636, simply in there being no guide-rail upon the center line of the resilient plate P. Such a guide-rail being dispensed with gives the reason for my automatic self-guiding trolleywheel. For making the construction of my third rail clearer to those who may not have my said application at hand I would briefly describe it as comprising the substantially flat resilient plate P, secured to the raised edges of the base P with a sheet of insulating material P separating said plate and base and an electroconductor P located close beneath the center line of the said plate.

What I claim as my invention, and desire to secure by Letters Patent, is as follows, to wit:

1. In combination,the plane-surfaced third rail, the trolley-wheel running thereon, bearings for said wheel adapted to resistingly per- Init a slight canting of the same, and means whereby such canting automatically guides said wheel toward the center line of the third rail, substantially as set forth.

2. In a trolley for third rails, the combination of the pivoted shank, the two parallel spring-arms carried thereby, bearing-boxes at the free ends thereof, the trolley-wheels revoluble in said boxes, and means for varyin g the downward pressure of said arms, substantially as andfor the purpose set forth.

3. In a trolley for third rails, the combination of the substantially horizontal, parallel spring-arms held at one end, means for forcibly depressing theirfree ends, a trolley-wheel revolubly carried by said free ends and having its peripheral face made crowning, substantially as and for the purpose set forth.

4. In a trolley for third rails, the combination of the substantially horizontal, parallel spring-arms given a limited spiral twist in opposite directions and rigidly held at one end, bearings at the free end of the same, and the trolley- Wheel having crowning peripheral face and loosely held in said bearings, substantially as and for the purpose set forth.

5. In a trolley for third rails, the combination of the tWo arms extending fore and aft from a single pivot, trolley-Wheels at their free ends, the right and left hand threaded nuts carried by said arm, and the correspondingly-threaded rod turning in said nuts and having means for its easy rotation, substantially as and for the purpose set forth.

6. In a trolley for third rails, the combination of the rigidly-held pin, F, the shanks,

D, D, pivoted thereon, oppositely-threaded nuts held by said shanks in vertical alinement, the correspondingly-threaded rod turning in said nuts and extended vertically, means for its easy rotation, the spring-arms rigidly held by said shanks, and the trolleywheels carried at the free ends of said arms, 3 5 

